The present invention relates to a method for detecting a moving object in motion video and an apparatus therefor, and, more particularly, to a method for detecting a moving object in motion video from the output of a video decoder and an apparatus therefor.
To detect a moving object present in motion video, it is generally necessary to check the motion of each pixel image. But, the pixel-by-pixel motion checking actually requires a vast amount of computation. In the case of the CIF format that is often used in H. 261 or H. 263 in ITU-T which is the international standard for video compression, MPEG-4 or the like of ISO/IEC, for example, it is necessary to detect the motion of each of a huge number of pixel images amounting to 101,376 pixels consisting of 352 pixels horizontal by 288 pixels vertical. Such a process that demands a vast amount of computation needs special hardware, which leads to an increased cost.
Jpn. Pat. Appln. KOKAI Publication No. 252467/1997 proposes a moving object detecting apparatus which employs a scheme of detecting a moving object from the motion vector that is generated by a video encoder. As this scheme can use a motion vector for each block generated by the video encoder in detecting a moving object, it need not to particularly check the motion of each pixel in order to detect a moving object. This scheme can significantly reduce the amount of computation needed to detect a moving object.
However, a block which shows a large motion vector or a rewritten block should not necessarily be a moving object. Further, a block which has not been rewritten may be present even in a block in a moving object. In consideration of adapting the moving object detecting method, which uses the aforementioned motion vector, to monitoring a moving object, this method may not be able to acquire needed videos.
As apparent from the above, the prior art requires a vast amount of computation to detect a moving object so that the conventional method that uses encoded video data does not provide a sufficient precision.